Johnson slides into Buchholz's rotation spot

ANAHEIM -- Left-hander Brian Johnson, ranked by MLB.com as the Red Sox's No. 5 prospect, will start and make his Major League debut on Tuesday against the Astros in Houston.

Johnson was called up on Saturday after the team placed Clay Buchholz on the 15-day disabled list with a strained right flexor tendon, near the elbow. 

Johnson went 8-6 with a 2.73 ERA in 16 games with Triple-A Pawtucket this season. He last pitched on July 6.

"Some things fell into place because of the break. It wasn't something we did to give him an extended period," said Red Sox manager John Farrell.

Johnson threw in an extended bullpen session on Thursday and will throw another light bullpen session on Sunday.

The team was deciding between starting Johnson on Monday or Tuesday. The starter for Monday's series finale against the Angels has yet to be announced.

Worth Noting

• Buchholz will see Dr. James Andrews on Wednesday for a second opinion on his injury.

"It is more peace of mind for him," Farrell said. "It's within his right to do that. We are supportive of it."